In the PLC ladder diagram, a coil is classified into many types as shown in the picture below.
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| Many options of coil types selection. |
As we can see in the picture below a coil could be an internal relay, an output pin on MCU or a Modbus. There are five different types of coil. Here we select the T-trigger (T) type. The letter T means 'toggle'.
A T-trigger coil changes (toggles) its output logic state whenever it's input change from low to high.
Let look at very simple example, I use an input contact to change the logic state of the output coil.
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| Toggle type coil ladder diagram example |
When the contact XC2 changes from false to true, the output coil changes its logic state.
We can make a circuit simulation in Proteus to verify the result.
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| Ladder diagram program example |
This program could run on an 8-pin PIC16F629 for convenience. My YouTube video show about a testing program on my DIY PLC board I made a few years ago.
Click here to download the zip file of this ladder diagram example.
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